Drawing press



' pRAwING PRESS FiledA April 29, 1942 JOH BY 'INVENTOR AN A. MULLER me.m

ATTRNEYS ating the press platen.'

A Patented 'July 27, 1943 OFFICE DRAWING PRESS Johan A. Muller. Dayton,

Hydraulic Development mington,

Corporation, Del., a corporation of Delaware Ohio, assigner to The Inc..Wil- Application April 29, 1942, Serial No. 441,042

14 Claims.

This invention relates to presses and, in particular, to hydraulicpresses having blank-hold ing arrangements in association with drawingdevices.

A well known type oi' presses of the above character comprises a pressplaten operated by a ram and provided with clamping cylinders, whichhave reciprocably mounted therein clamping plungers for actuating ablankholder platen. While this type of presses works verysatisfactorily, it has the clamping cylinders arranged separate from theram, thereby requiring machining of the press ram and the clampingcylinders in different machining setups.

It is, therefore, an object of the invention to provide an improvedblankholder press, which will enable machining of the press ram andclamping cylinders iny a single machining setup.

It is another object of the invention to provide a blankholder press, inwhich the press ram is provided with a recess conning a clampingcylinder for receiving the clamping plunger for actuation of theblankholder platen.

It is another object to provide an improved blankholder press with anincreased guiding length for guiding the blankholder means actu- It isstill another object of the invention to provide a blankholder presshaving a clamping cylinder piston arrangement for actuating theblankholder platen, in which the packing heretofore required forpreventing undue leakage from the clamping cylinder piston arrangementmay be' omitted without allecting the eiliciency ofsaid vclampingcylinder piston arrangement.

A still further object of the invention consists in the provision of ablankholder press in which the clamping plungers for actuating theblankholder platen are guided in the press platen and the press ram foractuating the latter.

These and other objects and advantages of the invention will appear moreclearly from the following speciilcation in connection with theaccompnying drawing diagrammatically showing a press according to thepresent invention.

General arrangement and extending into said press plunger means,v

which latter form a clamping cylinder.

The clamping cylinder in the press plunger means communicates with'auxiliary cylinder means through conduit means supported by said pressplunger means and adapted to telescope into said auxiliary cylindermeans.

Structural arrangement l Referring now to 'the drawing in detail, thestructure shown therein comprises a press head I with two main or presscylinders 2, 3, having respectively mounted therein press rams 4, 5.Each of the press rams 4, 5 is provided with a cavity 6, l, forming aclamping cylinder for co`k operation with clamping spectively.

The clamping plungers plungers 8 and 9 re- 8 and 9 are connected I Il inany convenient manner, for instance by screws II. Each of the clampingplungers 8 and 9 passes through bushings I2, I3 in the press platen I4and through packing I5, I6 in the rams 4, 45. The press platen I4 isconnected to the rams 4, 5 in any convenient manner, for instance bysplit rings I1 and I8 and screws I9.

The press platen I 4 carries a press plunger or die 20 adapted'to passthrough an opening 2| in the blankholder platen I D, which latter hasconnected thereto suspension rods 22, 23 respectively extending throughbores 24, 25 in the press platen I4, and having threaded thereto nuts26, 21 for abutment with the upper surface of the press platen I4 so asto maintain the clamping platen I0 suspended when the latter is spacedfrom the work piece to be shaped. Also connected with the press platenI4 is a control arm 28 adapted lto engage a collar 23 adjustably mountedon a push rod 30. 'Ihe push rod 30 also has adjustably mounted thereon acollar 3I for cooperation with an arm 32 of a threearm lever, generallydesignated 33, which lever is pivotally connected with a link 34 which,in its turn, ispivotally connected to an armature 35 controlled by asolenoid 36. The arm 31 of the three-arm lever 33 is connected through alinkage system 38 with a control rod 33 for controlling the position ofthe flow-control member pertaining to a reversible variable deliverypump 40 and adapted, in one position, to cause the pump 40 to deliverpressure iluid into the conduit 4I, while movement of the flow-controlmember into another position causes the pump 40 to deliver pressureiluid into the conduit 42.

ing the latter to actuate the armature .in its turn, shifts thethree-arm lever 33 and The conduit 4I leads to the upper portion of thepress cylinder 3, which upper portion is in continuous fluid connectionwith the upper .portion of the press cylinder 2 by meansof a conduit 43,a casing 44 and a conduit 45, branching oil from the conduit 45 andleading to a main cylinder relief and pump by-pass valve 41. Alsoconected with the valve 41 is a conduit 43 leading into the conduit 49and a conduit 49 connected with the conduit 50. One end of the conduit59 leads to a two-way valve 5I, while the other end of the conduit 50communicates with a conduit 52. The conduit 52 branches off from theconduit 42 and leads to a surge valve 53. The surge valve 53 may be ofany standard design, for instance of the type set forth in U. S. PatentNo. 2,193,248 to Ernst, and servesV to preilll the press cylinders 2 and3 during the rst portion of the downward strokes of the rams 4 and 5,during which the rams move downwardly by gravity.

The main cylinder relief and pump by-pass valve 41 serves to initiatethe retraction strokes of the press rams, and for a more detaileddescription of the said valve 41, reference may be had to U. S. PatentNo. 2,268,205 to Ernst.

The conduit 42 leads to the lower portion of the press cylinder 3, whichportion is connected by means of a conduit 54 with the lower portion ofthe press cylinder 2. The conduit 54 communicates with a conduit 55comprising a check valve 56 located in a iiuid reservoir or tank 51which houses the valves 41, 5I and 53. Also' connected with the uid tank51 are conduits 58 and 59 respectively comprising pressure relief valves99 and 8|, and leading to auxiliary cylinders 92 and 63 connected in anyconvenient manner with the press head I.

The cylinder 52 communicates with a conduit 54 comprising a check valve85 and communicating with a conduit 95. The conduit 55 comprises checkvalves 61 and 93 and leads to a conduit 69, which latter is connectedwith the cylinder 53 and comprises a check valve 10. The conduit 56 isalso connected with the two-way valve 5I by means of a conduit 1 I. Thevalve 5I is normally held by means of a spring, not shown, in such aposition as to prevent fluid connection between the conduit 1I and theexhaust conduit 19. However, in response to a predetermined pressure inthe conduit 50, the valve 5I overcomes the thrust of the said spring,thereby establishing fluid connection between the conduits 1I and 16.

Reciprocably mounted in each of the cylinders 52 and 93 are hollowauxiliary plungers 12' and 13 respectively, which latter are connectedto the rams 5 and 4, and establish fluid connecv tion between theinterior of the cylinders 32 and 93 and the cavities 9 and 1 in the rams5 and 4.

The plungers 12 and 13 pass through bushings 14 and 15 respectively,partly located in the auxiliary cylinders and partly located in thepress cylinders.

Operation It maybe assumed that all parts of the press occupy theposition shown in the drawing, and that it is now desired to cause thepress to perform a working cycle. To this end, the oper- -ator startsthe pump 40 in any convenient manner, and energizes the solenoid 35,thereby caus- 35 which,

the linkage system 39 so as to cause leftward movement of the controlrod 39.

As a result thereof, the pump is moved into full delivery forward strokeposition so as to deliver pressure fluid through the conduit 4I intovthe upper portion of the press cylinder 3. From here a part of thefluid ows through the conduit 43, casing 44 and conduit 45 into theupper portion of the press cylinder 2, while simultaneously uid iswithdrawn from the lower portion of the press cylinders 2 and 3 throughthe conduit-s 54 and 42. Therefore, the rams 4 and 5 move downwardly asfast as uid is withdrawn from the lower portion of the press cylinders 2and 3. The fluid delivered into the upper portion of the press cylinders2 and 3 is, at this time, supplemented by fluid passing from Vthe tank51 through the surge valve 53 and conduits 43 and 55 into the cylinders3 and 2.

Downward movement of the'rams 4 and 5 also causes the press platen I4,connected to said rams, to move downwardly, and inasmuch as theblankholder platen I0 is suspended on the press platen I4, also theblankholder platen I0 and the clamping plungers 9 and 9, connectedthereto, move downwardly.

The vacuum created in the auxiliary cylinders 62 and 63 by downwardmovement of the auxiliary plungers 12 and 13 connected to the ,rams 4and 5 respectively, is lled byuid passing from the tank through thecheck valves 65 and 10.

As soon as the blankholder platen I0 engages the work piece to beshaped, the blankholder platen comes to a halt, thereby also halting theclamping plungers 8 and 9. While the rams 4 and 5 are continuing theirdownward movement,

cylinders 1 and 6 respectively and, since the space occupied by saidclamping plungers 8 and 9 is larger than thev space released by thehollow plungers 12 and 13 in the cylinders 62 and 63, pressure begins tobuild up in the clamping cylinders 6 and 1 so as to cause theblankholder platen I0 to hold the work piece clamped at a certainpressure. Simultaneously the pressure in the clamping cylinders 6 and 1causes the check valves 65 and 10 to close.

It will be noted that, since the valve 5I at this time prevents fluidconnection between the conduits 1I and 16, no fluid can escape from theconduits 64 and 69 into the tank 51.

When the above mentioned pressure exceeds a predetermined value,corresponding to the setting of the pressure relief valves 60 and 6I,the excessive Apressure is released through said relief valves.The'press platen I4 and press plunger 20 now continue their downwardmovement, thereby drawing or shaping the work piece, held by theblankholder platen I0.

When the press plunger 20 has completed its drawing or shapingoperation, the operator deenergizes the solenoid 36, thereby allowing aspring, not shown, in the pump 40 to shift the flow-control rod 39toward the right so as to move the pump 40 into full delivery retractionstroke position. Pressure fluid is now delivered by the pump 40 into theconduit 42, from where it flows through the conduit 52 to the maincylinder relief and pump by-pass valve 41 to actuate the same so as torelease fluid from the upper portion of the press cylinders 2 and 3.

Furthermore, fluid from the conduit 52^is conveyed to thesurge valve 53to4 open the latter surge valve between the upper portion of the assautpress cylinders and the tank 61. Fluid also ows from the conduit 62 tothe two-way valve 6I and shifts the same so as to eilect iluidconnection between the conduits 1I and 16. l

Fluid pressure delivered bythe pump 46 into theconduit 42 is nowconveyed to the lower portion of the press cylinders 3 and 2 where-itcauses upward movement of the press rams and, thereby, of the pressplaten I4 and the press plunger 20. 'I'he uid expelled from the upperportion of the press cylinders during the upward movement of the pressrams passes through conduits 43 and 45 and the surge valve 63 in to thetank 51. Y While the rams 4 and 5 move upwardly, ythe press platen I4moves away from the blankholder platen hollow plungers 1,2 and 13 whenmoving into their respective cylinders 62 and 63. I! the fiuid expelledby the plungers 12 and 13 is not suilicient to fill the increased spacein the cylinders 6 and .1,

I so that the free space in the' clamping cylinders 6 and 1 increases.'I'his space issubstantially lled with uid expelled by the 3 to thepresent invention consists in that 6 and l throughout the width oi' thepress platen, and that the clamping plungers 6 and 3 and .6. In thisway. the clamping plungers 6 and 6 have a relatively large portioncontinuouslyA guided, so that with smaller presses no particular guidingAgibs for the The press platen, in this instance. is rigidly cona nectedwith the clamping plungers 6 and 3.

Since the clamping cylinders 6 and 1, according to the arrangementprovided in the rams 6 and 4. the bore through which the clampingplungers 6 and 3 extend into the cavities 1 and 6 maybe machined in thesame machining setup for machining the exterior" surface of the rams.I'he cavities 6 and 1 are cast and need no machining. In this way. thecosts of manufacturing the press according to the invention arematerially decreased over the costs-involved in machining cylinderpresses as heretofore known.

The provision of the cavities s and 1 in the rams 4 and 6 constitutes animportant saving in "thematerial for the rams.

whue the structure shown in the erewmg merelyv shows two press rams withtwo clamping cylinders therein, it is, of course,.understood that thearrangement may be multiplied. If desired,

- the press may be provided with some rams havand 1| through the two-wayvalve 5i and exhaust conduit 16 into the tank 51.

When the press platen Ill of its retraction stroke, the collar 29 isengaged by the platen arm 28 so that the push rod 30 is lifted andcauses the collar 3i to shift the threearm lever 33 in anti-clockwisedirection to such an extent that the control rod 39 moves the pump 40into substantially neutral or no delivery position. Consequently, nomore pressure fluid is delivered to the lower portion of the presscylinders 2 and 3 so that the press rams 4 and 5 come to a halt. Allparts now occupy the position shown in the drawing and the press isready for a new cycle.

From the above it will be seen that the cavities 6 and 1 act as clampingcylinders for cooperation with the clamping plungers 9 and 6 to exertthe desired clamping pressure on the blankholder platen I0. It will.furthermore be noted that, since iluid pressure is conveyed through thehollow plungers 12 and 13 into the auxiliary cylinders 62 and 63 fromthe cavities 6 and 1, the pressure in the avities 6 and 1 also acts uponthe marginal `or annular areas of the hollow plungers 12 and 13, therebyalso acting on the rams 5 and 4 connected to the plungers 12 and 13. Inother words, not the total pressure acting on the upper surface of theclamping plungers 8 and 9 is to be derived from the pressure acting onthe rams 4 and 5, but only the pressure acting on a clamping plungerarea, which equals the sectional area of the bores 11 and 18 in thehollow plungers 12 and 13.

It should also be noted that, since during the pressing operationpressure prevails in the cylinders 62 and 63 as well as in the upperportion of the press cylinders 3 and 2, it is quite suf- Il cient toprovide bushings 14 and 15 through and 13 pass and no packing approachesthe end ing clamping cylinders therein, 'and other rams having noclamping cylinders associated therei with.

It win be understood that I desire to comprehend within my inventionsuch modifications as come within the scope of the claims and theinvention.

Having thus fully described myinvention, what I claim as new vand desireto secure by Letters Patent, is:

l. In combination in a drawing press, a reciprocable press platen, fluidoperable plunger means for actuating said platen, said plunger j meanshaving a cavity therein conning a clamping cylinder, blankholder meansfor holding a being shapedpby pressure exerted 0n said press plungermeans .reciprocable in said clamping cylinder for actuating saidblankholder means, said clamping plunger means being arranged to createpressure in said clamping cylinder in response to the movement of saidpress platen toward said blankholder means.

2. In combination in a drawing press, a hollow press ram conilning aclamping cylinder, iluid operable advancing and retracting meansassociated Vwith said ram for reciprocating the same, blankholder meansfor holding a workpiece while it is being shaped by pressure-exerted .onsaid press ram, and iluid operable clamping plunger means reciprocablein saidclamping cylinder and operatively connected with said blankholdermeans for conveying pressure thereto.

3. In combination in a drawing press, a press ram having a cavitytherein forming a clamping cylinder, motor means for reciprocating saidram,

ram, and iluidoperable clamping plunger means reciprocable in saidclamping cylinder and responsive to a relative movement between said ramand said blankholder means for pressure in said clamping cylinder andsaid pressure to said creating conveying blankholder means. f

me bushings I2 and I3 guide the clamping "plungersare rurthermore guidedbythe lower end o! the rams 4 of the present'invention, are' platen, andclampingvv 4. In combination in a drawing press, a hollow press ramcomming a main clamping cylinder, fluid operable advancing andretracting means for reciprocating said ram, blankholder means forholding a work piece while it is being shaped by pressure exerted onsaid ram, main clamping plunger means reciprocable in said main clampingcylinder and operatively connected with said blankholder means forconveying pressure thereto, an auxiliary clamping cylinder, and a hollowauxiliary clamping plunger hydraulically interconnecting said main andsaid auxiliary clamping cylinders, said main clamping plunger meansbeing adapted in response to a relative movement between said ram andsaid blankholder means to create pressure in said'clamping cylinders.

5. In combination in a drawing press, a press platen, a plurality ofpress rams connected to said platen for actuating the same, each of saidrams being hollow and confining a clamping cylinder, fluid operableadvancing and retracting means for reciprocating said rams, blankholdermeans for holding a work piece while it is being shaped by pressureexerted on said platen, and a plurality of clamping plungers arrangedto-move with said blankholder means and respectively reciprocable insaid clamping cylinders for creating pressure therein in response to arelative movement between said press platen and said blankholder means,and for conveying said pressure to said blankholder means.

6. In combination in a drawing press, a press platen, hollow ram meansconfining clamping cylinder means, blankholder means for holding a workpiece while it is being shaped by pressure exerted on said ram means,clamping plunger means arranged to move with said blankholder means andreciprocable in said clamping cylinder means, and means for moving saidram means relative to said blankholder means for creating pressure insaid clamping cylinder means and conveying said pressure to saidblankholder means.

7. In combination in a drawing press, a press platen, fluid operablehollow ram means confining clamping cylinder means and connected to saidplaten for reciprocating the same, blankholder means for holding a workpiece while it is being shaped by pressure exerted cn said platen, fluidoperable clamping plunger means reciprocable in said clamping cylindermeans and guided by said platen for blankholder means, said clampingplunger means being adapted in response to a relative movement betweensaid platen and said blankholder means to create pressure in saidclamping cylinder means, and means for conveying fluid into saidclamping cylinder means.

8.' In combination in a drawing press, fluid operable hollow drawingplunger means, a press platen operable by said plunger means,blankholder means for holding a work piece While it is being shaped bypressure exerted on said drawing plunger means, and clamping plungermeans reciprocable in said drawing plunger means, said clamping plungermeans being connected to said blankholder means and operable by themotion of said press platen.

9. In combination in a drawing press, drawing cylinder'means, drawingplunger means therein, a press platen operated by said drawing plungermeans, clamping cylinder-piston-assernblies associated with said platenand operable automatically to create pressure therein in response to themovement yof said .drawing plunger means in conveying pressure to saiddrawing direction, the cylinders of said clampingcylinder-piston-assemblies being formed by said drawing plunger means. aclamping platen operable by said clamping cylinder-piston-assemblies forholding a work piece clamped while it is subjected to shaping pressureby said drawing plunger means through said press platen, auxiliarycylinders, auxiliary plungers movable in said auxiliary cylinders, meansfor conducting fluid between said clamping cylinder-piston-assembliesand said auxiliary cylinders, and a pressure relief device for eachauxiliary cylinder adapted to discharge fluid therefrom in response tothe attainment of a predetermined pressure therein.

10. In combination in a drawing press, a press head having a drawingcylinder, a hollow drawing plunger therein confining a clampingcylinder, a platen operated by said drawing plunger, blankholder meansfor holding a work piece while it is being shaped by pressure'exerted onsaid drawing plunger, a clamping plunger reciprocable. in said clampingcylinder and connected to said blankholder means for conveying pressurethereto, an auxiliary cylinder mounted on said press head, an auxiliaryplunger movable in said auxiliary cylinder and connected to said drawingplunger, means for conducting fluid between said clamping cylinder andsaid auxiliary cylinder, and a pressure relief device associated withsaid auxiliary cylinder and adapted to discharge fluid therefrom inresponse to the attainment 'of a predetermined pressure thereon, theworking surface of the head of said auxiliary plunger and said drawingplunger being positioned in similar direction relative to said platen,whereby the pressure fluid generated in said clamping cylinder duringthe clamping operation acts against the auxiliary plunger in the samedirection as the pressure exerted on said platen by said drawirg plungerduring the pressing operation thereo 1l. In combination in a drawingpress, a drawing cylinder, a hollow drawing plunger therein confining aclamping cylinder, a press platen operated by said drawing plunger,blankholder means for holding a work piece while it is being shaped bypressure exerted on said platen, a clamping plunger reciprocable in saidclamping cylinder and operable by movement of said platen relative tosaid blankholder means for exerting pressure on the latter, an auxiliarycylinder, an auxiliary hollow plunger connectedv to said clampingcylinder and reciprocable in said auxiliary cylinder, and a pressurerelief device associated with said auxiliary cylinder and adapted todischarge fluid therefrom in response to the attainment of apredetermined pressure therein.

l2. In combination in a drawing press, a drawing cylinder, a hollowdrawing plunger therein confining a clamping cylinder, a press platenoperated by said drawing plunger, blankholder means for holding a workpiece While it is being shaped by pressure exerted on said platen, aclamping plunger reciprocable in said clamping cylinder and operable bymovement of said platen relative to said blankholder means for exertingpressure on the latter, an auxiliary cylinder, an auxiliary hollowplunger connected to said clamping cylinder and reciprocable in saidauxiliary cylinder, a pressure relief device associated with saidauxiliary cylinder and adapted to discharge fluid therefrom in responseto the attainment of a predetermined pressure therein, a fluidreservoir, and valve means arranged automatically to prevent fluidconnection between said clamping cylinder and said iiuid reservoirduring the pressingoperation of said drawing plunger and adapted inresponse to the retraction stroke of said drawing plunger to establishfluid connection between said clamping cylinder and said uid reservoir.

13. In combination in a drawing press, a draws ing cylinder, a hollowdrawing plunger reciprocable in said drawing cylinder and confining aclamping cylinder, blankholder means for holding a work piece whileshaping pressure is exerted' 14. In combination in a drawing press, apress platen, a drawing cylinder, a. hollow drawing 4plungerreciprocable in said cylinderA for actuating said press platen, saiddrawing plunger conilning a clamping Vcylinder,-blankholder means forholding a work piece while ii; is being shaped l by pressure exerted onsaid press platen, a fluid operable clamping plunger reciprocable insaid clamping cylinder for conveying pressure to said blankholder means,said clamping plunger extending through said press platen and beingmovable relative thereto, means in said press platen for'guiding saidclamping plunger, an auxiliary cylinder, means for admitting uid to saidauxiliary cylinder, and a hollow auxiliary plunger supported by saiddrawing plunger and reciprocable in said auxiliary cylinder forcontinuously establishing hydraulic connection between said clampingcylinder and saidv auxiliary cylinder, said clamping plunger cooperatingwith said clamping cylinder for creating pressure therein in response tothe movement of said press platen toward said blankholder means. y

i JOHAN A. MULLER.

